Aircraft



Jan. 19, 1937. E B, WIL ORD 2,068,616

AIRCRAFT Filed July 1'7, 1933 2 Sheets-Sheet 2 INVENTOR. EDWARD B. WILFORD ATTORNEY.

Patented Jan. 19, I937 lTED STATES PATENT OFFICE 10 Claims.

This invention relates to aircraft, and particularly to gyroplanes.

In certain types of aircraft as provided in the past, there have been utilized combinations of both rotary and fixed wing systems. However, this conjoint use of the past was due to a neces sary compromise whereby ailerons and the like were mounted upon fixed wings, to furnish the controlling moments not obtainable fro-m the rotating'wing system. The fixed wing was also of sufficient area as to keep the rotative speed of the rotor substantially constant by assuming perhaps 20% of the load in forward flight, The conjoint use of the past, however, simply aggregated the disadvantages of each system to militate against any advantages inherent in either system alone.

In considering the problems of gyroplanes it must be recognized that there are two principal conditions to which the device must be responsive. First, to forward flight, and, second, to vertical movement with or without forward movement. These conditions and combinations thereof are found in climbing, flying level and cruising, and in descending.

In gyroplanes of the past the major load has been disposed upon the rotor under all service conditions, and this has resulted in the creation of such drag in the rotating wing system as to seriously affect the maximum forward speed of the aircraft, and owing to the fact that the only control system was disposed on the fixed wing has required forward movement to secure control. Any condition of direct descent, for instance, without forward movement has found the aircraft to be out of control. This has effected a sharp limitation on the speed range of gyroplanes of the past, and has provided inefiicient control thereof.

For certain purposes it is of considerable moment that in the gyroplaneof this invention there should be control in the rotary wing system itself in synchronism with the normal control surfaces of the aircraft, such as ailerons upon the fixed wing system. While there may be considerable variation in the types of rotor control that are utilized, it is preferred for some purposes to use a rotor control such as is disclosed and claimed in Rieseler and Kreiser application Ser. No. 479,037. A specific hookup or connection of the rotor control and conventional control surfaces of an aircraft is disclosed and claimed in an accompanying application now in course of preparation, which will be understood to be incorporated in the gyroplane according to the inpose the major part stant invention. As will be pointed out the'con joint use of two distinct control systems in connection with the conjoint use of two distinct supporting systems provides a gyroplane which is always under perfect control regardless of the presence or absence of forward speed.

It is among the objects of this invention; to provide a gyroplane with both rotary and fixed wing systems, and arranged selectively to disof the load upon either the 0 rotary or the fixed wing system; to provide anairplane with a rotating wing system such that the latter can be used for supporting the major load during descent, but to be relieved of its major load during forward flight; to provide air- 5 craft having a rotating and a fixed wing system in which the load can be carried upon the fixed wing to unload the rotor, whereupon the speed of rotation of the rotor can decrease with safety and with reduction of its drag to such minimum 9 as to have substantially no adverse effect upon the forward speed of the whole; to provide a substantially rigid rotor the speed of which can be raised or lowered without collapse thereof, with a fixed wing such that the load can be substantially shifted from the rotor to the wing and from the wing to the rotor, with a consequent utilization of the most eflicient factors of each; to combine in an aircraft a rotary and a fixed wing and control system in which the favorable factors of each are present as and when desired, thus that the low L/D of the rotary system furnishes the lift for safe and slow descent with positive control, and the. fixed wing system furnishes the high L/D for rapid forward flight with normal con-' trol, with the rotor flying on edge to reduce its rotative speed and its minimum drag to secure a high ratio between maximum lift and minimum drag of the aircraft as a whole; to provide a rudder on an inclined axis such as to give rudder 40 controlling actions to turn the aircraft about a substantially vertical axis when the aircraft is moving either directly horizontal or directly vertical as well as on intermediate flight paths; to provide a safe and useful multimotored aircraft 5 with roomy body and comfort to the passengers with a rotor for descent and take off in restricted areas, and with a fuselage of airfoil contour which may or may not be combined with a small fixed wing, for unloading the rotor in forward flight to secure efiicient performance; and many other objects and advantages as will become more apparent as the description proceeds.

In the accompanying drawings:

Fig. 1 represents an elevation of the aircraft of this invention in normal forward flight relative to the indicated direction of air fiow, and in-which the rotor has been unloaded and is idling, with the major load on the fixed wing,

Fig. 2 represents a similar elevation in which the rotor speed has increased, and the major load is on the rotor and the aircraft is ascending or descending,

Fig. 3 represents a .diagrammatic illustration of the relative angles of the component parts of the aircraft to secure favorable results according to this invention,

Fig. 4 represents a diagrammatic disclosure of the coupled synchronized control systems for the rotor and the ailerons and elevator of the aircraft, such as is available to enhance the utility of the invention, I

Fig. 5 represents a front elevation of a modified form of the invention herein utilizing a fuselage of airfoil contour, and

Fig. 6 represents a side elevation of the same.

Referring to Figs. 1 and '3 a purely illustrative form of the invention is disclosed in which a fuse-v lage l having a longitudinal axis as line C of Fig. 3,'as a motor or power plant ll, propeller l2, landing gear l3, and a rudder l4 disposed to swing upon the inclined axis I found on the trailing edge of fin 1 so as to give rudder controlling actions during direct vertical motions of the aircraft about substantially vertical axes of the aircraft in either horizontal or vertical movements of the aircraft. The advantages and operation of the rudder M will be obvious. The fuselage may also carry a horizontal fin 8 and elevator control surface 9.

Suitably supported upon a pylon I6 is a rotor or rotating wing system I! lying substantially in an average plane D (Fig. 3), ha a substantially vertical axis of rotation, perpendicular to the average plane of system H and preferably substantially perpendicular to the longitudinal axis C of the fuselage l0. While there may be.

other forms of rotary wing systems or rudders used in connection with this invention, yet -for illustrative and explanatory purposes the type of wing system shown in Rleseler and Kreiser reissue application No. 545,362, or in my co-pending application Ser. No. 478,990 or in my co-pending application Ser. No. 571,946, or the like may be used, the only essential in the rotor according to this. invention being that it hold its position, substantially regardless of centrifugal force. For illustrative purposes the rotor l1 will be considered to include a pair of blades or wings l9, oscillatable on an axis 20 to equalize the effective lift on opposite sides of the rotor, as well as to predeterminedly vary the efiectivelift so as to secure desired predetermined controlling moments by some such mechanism as is hereinafter described in connection with Fig. 4. While the rotor I1 is preferably arranged for aerodynamic rotation when the relative airstream strikes the rotor at proper angles, yet his also so arranged as to decelerate to a condition of slow rotation owing only to "profile drag, when the relative airstream strikes the rotor at small .argles. This .slow rotation is due purely to the fact that the advancing airstream exertsmore drag-on the trailing edge of a blade than on theentering edge thereof. It is preferred that the rotor be permitted to rotate slowly at small angles of attack, during which, obviously, there is no lift available from the rotor, or'the rotor may be caused to come to a complete stop and beheld against any sort of the minimum of drag and trouble.

It is a feature of importance "that control of the aircraft be derivable from the rotor, as in accordance with the Rieseler and Kreiser application Ser. No. 479,037 or in accordance with the companion application co-opending herewith, so that rolling and pitching controlling moments may be secured for the aircraft from the rotor regardless of the presence or absence of forward speed. As noted, such control system will be described later herein. As a further alternative, but less desirable type of control, that may be utilized in the connection, it is contemplated that the rotor l'l maybe universally mounted on'the pylon I6 in such manner that its axis of rotation may be predeterminedly shifted to control the attitude of the aircraft.

For general purposes it may be assumed that the axis of rotation of the rotor system H is substantially perpendicular to the longitudinal cenfixed wing l8, the base or datum line' E (Fig. 3),

of which is angularly divergentfrom the longitudinal axis C of the fuselage. At least it is in non-parallel relation to the plane of the rotary wing system or to the general or average plane of a coning rotary wing system, and to the longitudinal axis of the aircraft, but the degree of angular, divergence will depend upon conditions encountered in the particular rigging, etc. of the aircraft in question. For purely illustrative and not limitative purposes the base or datum line E, of the relatively fixed wing l8, diverges angularly from the longitudinal axis 0, and from the plane or general or average plane substantially perpendicular to the axis of rotation of the rotary wing system by substantially 4. That is,,such setting has been found satisfactory in one device, but obviously may be greater or smaller than that angle. It is a feature of refinement or increased efliciency that the wing l8 be arranged foradjustment about axes lateral of the fuselage so that fore function either in whole or in part as the fixed wing system by which some or all of the load of the aircraft may be carried when the rotor is unloaded. In this just described modified form it is preferred that the fixed wing l8 be of reduced span and area, and may be provided at any vertical position on, and, in addition to, the airfoil fuselage to form a low, middle, or high wing monoplane, if a monoplane is to be utilized. It will be 'clear'that effective results can be had from a plurality of fixed wings, if preferred, in any embodiment of this invention.

As pointed ,out in the noted co-pending application, there may be many modifications of. the synchronous. controlling systems, and that which is diagrammatically shown in Fig. 4 is to be considered as purely illustrative. A master control device as stick 22 is provided, suitably pivoted as at its lower end (for instance) on a transverse pivot in horizontal rock shaft or torque tube 23, which carries perpendicular lug 24 and transverse rotor rock shaft 25, the ends of which are pivotally engaged by the crossed links 26 and 21. in turn pivotally engaging with the substantially universally pivoted device indicated by the intersecting lines 28 and 30 carrying the substantially vertical rotor control member 3|. The pivoted device 28, 30 is also pivotally engaged by links 32, 33, pivotally engaging the free ends of a T-shaped compound bell crank lever 34, the depending arm 35 of which is pivotally engaged by the link 36 pivoted to the control stick 22. A link 31 engages with a horn or the like 38 of the elevator surface 9 and with control stick 22. The ailerons 2| have actuating horns 40, engaged by links 4 I, pivoted to bell crank levers 42, the opposite ends of which connect with transverse links 43 and 44 pivoted to the lug 24 on rock shaft 23.

The rotor I! is comprised of as many blades as desired, of which for purely illustrative purposes, two are shown at H3, in Fig. 4, mounted for oscillation about the axis 20, and the angular position of which is controlled by the linkage to the control member 3|, the angular position of which relative to the vertical, or to the axis of rotation of rotor I1, is variable according to pull on the links 32, 33 and 26, 21. Such control may be secured as desired, but in the illustrative disclosure comprises a control horn or lug 45, the position of which determines the position of one blade 19, and a control lug or horn 46 operatively associated with and controlling the position of the other wing or blade i9, with mechanism comprising links 41 and 48, ball crank rock shafts 50 and 5|, and links 52 and 53 engaging vertical control member 3|. It will be understood that a single movement of master control device 22 in a generally fore and aft line, simultaneously actuates elevator 9, as well as the rotor control member 3| in such manner as to secure pitching moments from the respective blades l9 at the same time as such pitching moments are secured from the elevator 9 if the relative forward speed is sufficiently high. Obviously also, lateral movements of master control 22 simultaneously actuate ailerons 2|, and also rotor control member 3| so as to secure lateral rolling moments from the respective blades l9 if the rotor speed is sufiiciently high. Compound control stick movements obviously secure compound synchronized controlling movements as will be clear.

The important thing is that synchronized controlling movements are secured although the one that is most effective depends entirely upon relative forward speed or its absence.

With the aircraft of this invention disposed as in Figs. 1, 5 and 6, with the relative airstream moving parallel or substantially parallel to the longitudinal axis of the. aircraft, there will be substantially zero or at least such small angles of attack of the rotating wing system II that it may decelerate to idling condifdon, and with a consequent substantial failure to assume any appreciable part of the load. This angular disposition, however, finds the fixed wing, whether wing l8, fuselage Ill or 22, or both wing l8 and fuselage -22, at favorable angles of attack or incidence such as to maintain the efllcient load supporting horizontal flight at cruising or high speeds and with such high efliciency as such fixed wing systems may attain, except for such decrease as is due to the relatively small e drag by which the rotor is kept idling, or hichthe rotor exerts when held against rotation. At this runs on the wing time the dual control, namely, the rotor control and conventional control system including aile- 'l8, are being actuated by the pilot but no controlling moments are available from the rotor, although high efliciency in control is available from the fixed wing and tail control surfaces during this time.

If the speed of the aircraft should diminish so as in effect to change the angle of incidence thereof, or if through actuation of control surfaces the actual angle of attack of the aircraft should be changed, as, for instance, toward a climb, the relative airstream would change its angle relative to the average plane of the rotor system I! so that its relative motion would cause aerodynamic acceleration of the idling rotor H to cause it to generate such lift as to begin to assmne the load of the aircraft. Owing to the rigidity of the rotor system H and to the fact that its position is maintained substantially regardless of its rotative speed, the application of the load to the rotor causes simply an acceleration in its rotation, and not its collapse, and the only deterrent factor militating against instantaneous assumption of the load is the inertia in the system. During this period of change of effective angle of attack of the aircraft, the angle of incidence of the fixed blade i8 has obviously been increased so that there has been an increase in drag from the fixed wing l8 but there has been also an increase in its lift and at this time the load is carried by both the rotor and fixed wing systems. It might be observed that the down wash from the rotor system I1 is helpful in keeping the lift of the wing |8 at an efilcient point even after the angle of the wing l8 to the relative airstream has increased beyond what would otherwise be the burble point thereof. During this time of support of the load upon both the rotor and fixed Wing systems, it will be clear that the controlling moments of the aircraft are derivable from both the rotor and the fixed wing and conventional controls.

With a further effective increase in the angle of the relative airstream and the aircraft, such for instance as a complete loss of forward speed, the vertical descent of the aircraft finds the rotary wing system H assuming substantially all of the load while the upwardly moving relative airstream eddying about the fixed wing I8 has substantially only a drag coeificient, which, however, being vertical imparts effective lift to retard the descent. During this interval the control of the aircraft is derivable solely from the rotary win tem II.

It will be clear that the on its inclined axis IE will be able to generate moments about thevertical axis of the aircraft during all conditions of flight from purely vertical to purely horizon It will be clear that with this invention the only time the undesirable characteristics of the fixed wing are present and noticeable, such as drag and inadequate control at high angles and slow or no forward speed, is when the rotor is loaded, and no liftis needed from the fixed wing and adequate control is available from the rotor per se. On the other hand, for cruising, the high drag factor of the rotating wing system is eliminated and rendered practically unnoticeable, by unloading the rotor and permitting the rotor to reduce its speed of rotation to that occasioned only by the profile drag of the system. While,

rudder [4, working as noted, the rotor may be arrested in rotation yet it is preferred that it be simplyslowed down so that the reduced speed of rotation is just enough to keep the rotor'in condition to assume the load and to speed up when it is called upon.

It will be evident to those skilled in the art that the relativeareas of, the rotary and fixed wing system have an important'bearing upon the success of the invention, each being so set as to furnish enough lift to take its load at the angle of best compromise for high and low speeds so that the areas and angles are so proportioned as to secure the best results.

The existence of the synchronous control system in both the rotary and fixed wing systems bridges the problem of control under varying conditions of forward flight, andthe result is not only a high safety factor, owing to complete control at all speeds but also of a high speed range for the aircraft.

It is pointed out further as a fundamental object of the invention in gyroplanes that the provision of a fixed wing system as auxiliary to and complemental of the rotary wing system and of such relative area and relative angle as to assume the major load, is for the further purpose 'of permitting the rotative speed of the rotary wing'system sharply to diminish whereas fixed wings of the past have only assumed small portions of the load and the object was simply to prevent the rotative speed of the rotary wing system from increasing or decreasing. In a rotor which is acting in auto-rotation and supporting a load, the rotative speed varies substantially as the square root of the load, and only very slightly, say not over 20% with maximum possible variation in the forward speed, so that in a gyroplane equipped with a fixed wing system the assumption of the load by the fixed wing system has the direct effect of reducing the revolutions or rotative speed of the rotor. As used heretofore, the combination of fixed and rotary wing systems has been for the sole purpose of keeping the rotor speed substantially constant, by nullifying the slight variation in rotor speed incident to variation in air speed. Obviously the objects sought and results obtained are radically different.

I claim:

'1. In aircraft, a stationary wing system, it normally aerodynamically driven rotor of a substantially fixed coning-angle in which part at least of the thrust load is carried by moments in the spars and in which the revolutionary speed varies as the load carried thereby relative to that of said fixed wing, the stationary wing system so set that the no-lift line thereof is angularly rearwardly divergent from the substantial plane of said rotor, the whole so constructed and arranged that when the craft is flown in its higher speed range a considerable portion of its load is carried on the fixed wing system and the rotor is at such an angle that the autorotative speed and hence the rotor drag is materially and safely reduced, and whereby eflicient high speed flight is enhanced.

2. In aircraft, a rotor having blades the coning angle of which is substantially independent of the disc loading and which angle is alsosubstantially independent of rotative speed, a fixed wing system so set that its'no-lift line isrearwardly downwardly divergent from the average plane of the rotor, the whole so constructed. and arranged that when the craft is flown with the fixed wing carrying the major part of the load in high speed flight the rotor is at such an angle that the loading of the rotor is materially and safely reduced, and so arranged that when flown at such an angle 'of attack and speed that the load on the fixed wing is substantially reduced in its slower speed range a considerable portion of the load is shifted safely from the fixed wing system to the rotor, whereby the drag is reduced in high speed flight.

3. In aircraft, a normally aerodynamically driven rotor of substantially fixed coning angle in which the revolutionary speed varies directly as the load carried by the rotor, a stationary wing system whose no-lift line is set so as to be rearwardly downwardly divergent from the substantial plane of the rotor, the whole being so constructed and arranged that at the higher speeds and high angles of attack a considerable portion of the aircraft load is carried by the fixed win system while the remaining portion of the load is carried by the rotor which consequently has a I slower rotative speed and reduced drag and so arranged that at slow speeds and high angles of attack the rotor safely assumes and supports a considerable portion of the load, whereby the drag is reduced at higher speeds.

4. In aircraft, a' normally aerodynamically driven rotor'having blades which are cantilever and substantially non-flapping and in which the principal part of the thrust load of the rotor is carried by bending moments in the spars and in which the revolutionary speed varies directly as the load carried by the rotor, a stationary wing system whose no-lift line is set so as to be rearwardly downwardly divergent from the average plane of the rotor, the whole so constructed and arranged that when the craft is flown at such an angle that the major load is carried on the fixed wing system the rotor is at such an angle that the autorotative speed is materially reduced and hence its drag is low.

5. In aircraft, a normally aerodynamically driven rotor having blades the coning angle of which is substantially independent of disc loading,

a fixed wing system so set that its no-lift line is rearwardly downwardly divergent from the plane of the rotor, the whole so constructed and arranged that when the craft is flown at its higher speeds the major part of the total load is carried on the fixed wing system andthe rotor is at such an angle that the loading of the rotor is materially and safely reduced so that its speed is materially decreased to reduce the drag thereof, whereby the drag is decreased in high speed flight.

6. In aircraft, a normally aerodynamically driven rotor having blades, the coning angle of which is substantially independent of disc loading, a fixed wing system so set that its no-lift line is rearwardly downwardly divergent from the substantial average plane of the rotor, the whole so constructed and arranged that when the craft is flown at its higher speeds the major part of the total load is carried on the fixed wing system and the rotor is at such an angle that the loading of the rotor is materially and safely reduced so that its speed is materially decreased to reduce the shiftedsafely from the fixed wing system to the I rotor, whereby in high speed flight the drag is reduced.

7. In aircraft, a rotor in which part at least of the thrust load. is carried by the spars acting as cantilever beams and in which the revolutionary speed .varies as the proportion of the total load carried thereby, a stationary wing system so set that the no-lift-line thereof is downwardly rearwardly divergent from the substantial plane of said rotor, the rotor and fixed wing system being so constructed and arranged as alternatively select'ively to support an appreciable part of the total load on either the rotor or fixed wing system, whereby drag at high speeds can be safely reduced.

8. In aircraft, a normally aerodynamically driven rotor having blades the coning angle of which is substantially independent of rotative speed, a fixed wing system so set that its no-lift line is rearwardly downwardly divergent from the average plane of the rotor, the rotor and fixed wing being so constructed and arranged as alternatively selectively to support the major load part of the total on either rotor or fixed wing system, whereby drag at high speeds can be safely reduced.

9. In aircraft, a feathering normally aerodynamically driven rotor in which the major thrust load of the rotor is carried by bending moments in the spars which are supported as cantilever beams and in which the revolutionary speed varies directly with the'imposed proportion of the total load, means "for selectively feathering the blades of the rotor for control purposes, a fixed wing system including ailerons and an elevator, means for selectively actuating the ailerons and elevator for control purposes, the fixed wing system being so set relative to the average substantial plane of the rotor as to have its no-lift line form a rearwardly divergent angle, the whole so constructed and arranged as alternatively and selectively to support the major load on either the rotor or wing system, whereby drag at high speeds can be safely reduced, and a common control operatively associated with both said last mentioned means to actuate said rotor control means and fixed wing system control means so as to secure an effective control substantially proportionally on the rotor or wing system that is carrying the major load.

10. In aircraft, a rotor having blades the coning angle of which is substantially fixed and is substantially independent of disc loading, a fixed wing so set that its no-lift line is rearwardly downwardly divergent 'from the substantial average plane of the rotor, means for securing stabilizing controlling functions from the rotor, means for securing stabilizing control functions from the fixed wing system, the whole so constructed and arranged that alternatively and selectively the major part of the total load can be carried upon either the fixed wing system or the rotor, and

common means for actuating the said two stabillzing and controlling means so as to be effective proportionally substantially to the proportion of the total load carried by the rotor or fixed wing system.

EDWARD BURKE WILFORD. 

